Biomedical subjects

L R Lee

Publications and source records attributed to L R Lee.

At least 19 recordsLinked to original sources

PubMed2001

Temperature effect on nausea during fluorescein angiography.

PURPOSE: Nausea is the most common adverse effect of fluorescein angiography (FA). Warming of fluorescein dye before injection has been reported anecdotally to decrease nausea frequency. We examined the effect of warmed fluorescein dye on the frequency of adverse effects of FA. DESIGN: Prospective, randomized, controlled trial. PARTICIPANTS: Five hundred forty-seven angiograms performed on 394 patients; 273 were in the control group and 274 were in the study group. METHODS: Patients were alternately assigned to FA using dye at room temperature (control group) or dye prewarmed to body temperature (study group). All patients were masked to the dye temperature. After FA, patients were questioned regarding any adverse effects experienced. MAIN OUTCOME MEASURES: Presence or absence of reported nausea associated with FA. RESULTS: Adverse reactions were reported for 39 of the angiograms (7.1%), including 32 procedures for which nausea was reported (5.9%). No significant difference in the frequency of adverse reactions was found between the two groups (P = 0.41). No significant difference in the frequency of nausea was found between the two groups (P = 0.28). The sample sizes used allow an 80% power for detecting a clinically significant difference of 4% adverse effects in one group and 10% in the other group when testing at a significance level of 5%. CONCLUSIONS: Warming of fluorescein dye does not significantly alter the incidence of nausea reported with FA.

Female↗

PubMed2000

Localized neurofibroma of the orbit: a radiographic and histopathologic study.

PURPOSE: To demonstrate the clinical, radiographic, intraoperative and histopathologic presentation of a localized neurofibroma of the orbit. METHODS: Clinicopathologic case report. RESULTS: A 25-year-old man was examined for inferior displacement of the right globe. Physical examination and neuro-imaging identified a localized solid tissue mass of the superior orbit. Histopathologic evaluation after complete surgical resection proved the lesion to be a localized neurofibroma. CONCLUSIONS: The patient's history, clinical presentation, and imaging studies were strongly characteristic for this infrequently encountered orbital lesion. Several imaging features, including multilobulation, multiplicity, ring-configured contrast enhancement, and magnetic resonance imaging (MRI) signal intensity heterogeneity, when present in combination, may be reasonably diagnostic of this tumor.

Adult↗

PubMed2000

Expression of proliferating cell nuclear antigen in luminal epithelium during the growth and regression of rat uterus.

Proliferating cell nuclear antigen (PCNA), a processivity factor of DNA synthesis, has often been used as a marker that reveals proliferating cells. However, it also plays a role other than in DNA replication. The aim of this study was to examine the relationship between the expression of PCNA and cell proliferation, and also its relation to cell death in the uterine epithelium under various hormonal conditions. Rats with regular estrous cycles were killed at various stages of the cycle, and their uteri were removed for the detection of PCNA and apoptosis by immunohistochemical and terminal deoxynucleotidyl transferase-mediated nick end-label staining respectively. There was an inverse relationship between the expression of PCNA and apoptosis in the uterine epithelium during the estrous cycle. From diestrus to proestrus, the expression of PCNA increased, and few apoptotic cells were detected in the luminal epithelium. However, at estrus, apoptosis occurred markedly, and the expression of PCNA disappeared. To study further the effects of estrogen on PCNA expression and cell growth in the uterus, rats were ovariectomized and then implanted s.c. with estrogen capsules 2 weeks later. In ovariectomized rats, only a few PCNA-positive cells were observed in the uterine epithelium. After estrogen treatment, PCNA was expressed strongly in the luminal and glandular epithelia. In these rats, the removal of estrogen capsules resulted in apoptotic death and surprisingly strong PCNA expression in the cells of luminal epithelium. Our results demonstrate that PCNA is expressed not only in the estrogen-stimulated uterine growth, but also in the processes of regression induced by the withdrawal of estrogen. Although the expression of PCNA has been reported to represent cell proliferation, our results implicate functions other than cell replication for PCNA in the uterus.

Animals↗

PubMed1998

Angle-closure glaucoma after laser treatment for retinopathy of prematurity.

Laser photocoagulation has become the standard for treatment of retinopathy of prematurity. In general, it has been found to be a safe and effective means of retinal ablation. We report a case of angle-closure glaucoma in an infant after diode laser treatment for retinopathy of prematurity, which required bilateral surgical peripheral iridectomies.

Child, Preschool↗

PubMed1998

External argon laser choroidotomy for subretinal fluid drainage.

PURPOSE: To evaluate the efficacy and safety of external argon laser choroidotomy for drainage of subretinal fluid (SRF) during scleral buckling procedures for the repair of rhegmatogenous retinal detachments. METHODS: Fifty eyes of 50 consecutive patients presenting to a hospital-based retinal outpatient clinic with rhegmatogenous detachments underwent choroidotomy with argon endolaser for SRF drainage. The laser parameters used were 0.5s duration and 0.8W power. The primary outcome measures were successful drainage of SRF and incidence of complications. The drainage was considered successful if it was sufficient to complete the planned scleral buckling procedure. The extent of subretinal haemorrhage was graded. RESULTS: The mean age of patients was 55 years (range 16-80 years). Successful drainage of SRF was obtained in 47 eyes (94%). The complications observed at the drainage site included subretinal haemorrhage of less than 1 disc diameter in six eyes (12%) and retinal perforation in one eye (2%). CONCLUSION: External argon laser choroidotomy appears to be an effective method of draining SRF in rhegmatogenous retinal detachments.

Adolescent↗

PubMed1997

Orbital squamous cell carcinoma following retinal detachment surgery.

BACKGROUND: Orbital squamous cell carcinoma following retinal detachment surgery is a rare condition. A proposed pathogenesis involves implantation of conjunctival squamous epithelium at the time of surgery, with subsequent malignant transformation. METHODS/RESULTS: An 81-year-old Caucasian man presented with a six-month history of a discharging painful red right eye. Ten years earlier a right scleral buckling with an encircling sponge exoplant had been performed. Examination revealed exposure of the sponge, and a large mass in the superomedial conjunctival fornix. Computed tomography revealed a mass invading around the globe in the region of the exoplant. Biopsy revealed squamous cell carcinoma. Orbital exenteration was performed. CONCLUSION: Orbital squamous cell carcinoma may arise following retinal detachment surgery presumably due to iatrogenic conjunctival implantation deep in the orbit.

Aged↗

PubMed1997

Aeromonas sobria endophthalmitis.

BACKGROUND: Aeromonas sobria causes a rare Gram-negative bacterial water-borne infection. It has been found in waters of North Queensland and South-east Asia. Of all Aeromonas species, A. sobria is the most virulent and invasive and has been reported to cause soft tissue infection and corneal ulcer. METHODS: A 14-year-old Caucasian male from North Queensland presented following a penetrating eye injury in which a water bird (cormorant species) had pecked his eye while he was fishing. A fulminant endophthalmitis developed despite treatment with intravenous, intravitreal and topical antibiotics and initial wound repair. Enucleation was performed. RESULTS: Aeromonas sobria was isolated from the vitreous aspirate. CONCLUSION: Aeromonas sobria infection should be suspected in water-contaminated penetrating eye injuries. The prognosis in this case was poor.

Adolescent↗

PubMed1996

Intralenticular metallic foreign body.

BACKGROUND: Intralenticular metallic foreign bodies may be well tolerated for many years. CASE REPORT: A 24-year-old caucasian man was referred with an intralenticular metallic foreign body present in the left eye for five days. Following initial treatment with topical steroid and antibiotic, the lens remained clear and visual acuity normal. Two years later the left eye developed an anterior uveitis, with reduced vision. A left phacoemulsification lens extraction with removal of the intralenticular foreign body and insertion of a posterior chamber intraocular lens was performed. CONCLUSION: Management of intralenticular metallic foreign bodies may be conservative till intraocular inflammation or cataract develops.

Accidents, Occupational↗

PubMed1996

Keratoconus: the clinical experience of a Brisbane ophthalmologist.

Keratoconus is a common corneal dystrophy. In order to characterize an Australian experience with this condition, a retrospective study of 295 consecutive cases of keratoconus presenting to one Brisbane ophthalmologist (GR) was performed. The majority (82%) of patients presented before the age of 40 years. Keratoconus was bilateral in 240 (81%) patients and unilateral in 55 (19%) patients. Family history of keratoconus occurred in 43 (15%) patients. A history of atopy and eye rubbing was obtained in 131 (44%) and 30 (10%) patients, respectively. Follow-up after a mean +/- SD of 5 +/- 5 years was obtained in 188 patients. Treatment modalities at follow-up included rigid gas-permeable contact lenses (CL) (48%), PMMA CL (3%), corneal graft (25%), no treatment (13%), spectacles (9%), soft CL (2%). The annual corneal graft rate was 3% per year per eye. With careful contact lens fitting most keratoconus patients will not require a corneal graft.

Adolescent↗

PubMed1995

Clinical detection of unilateral keratoconus.

PURPOSE: To determine the incidence of true unilateral keratoconus on the basis of computerised corneal topography in a group with clinically diagnosed unilateral keratoconus. METHODS: Retrospective review of 295 patients with keratoconus identified 51 patients with a provisional diagnosis of unilateral keratoconus. Thirty-one of these patients were re-examined clinically and 21 patients met the criteria for a clinical diagnosis of unilateral keratoconus. Computerised corneal topographic analysis (Tomey TMS) was then performed. RESULTS: In a group of 21 patients with clinically diagnosed unilateral keratoconus, computerised corneal topographic analysis identified 14 (67%) patients with bilateral keratoconus and seven (33%) patients with true unilateral keratoconus. Contact lens wear had no significant influence (P=0.76) on the topographical diagnosis of keratoconus in the clinically unaffected fellow eye. The estimated incidence of true unilateral keratoconus in the cohort of 295 patients was 4%. CONCLUSIONS: Computerised corneal topography improves sensitivity in detection of true unilateral keratoconus.

Adult↗

PubMed1995

Blepharophimosis syndrome: association with colobomatous microphthalmos.

OBJECTIVE: To highlight the association of colobomatous microphthalmos with blepharophimosis syndrome. RESULT: We present a case of blepharophimosis syndrome associated with bilateral optic disc, retinochoroidal and iris colobomas, and microphthalmos, in a Caucasian boy. Inheritance in this case was autosomal dominant from the maternal side. CONCLUSION: Colobomatous microphthalmos is an infrequent ocular abnormality in the blepharophimosis syndrome. Ophthalmologists should be aware of this association.

Child, Preschool↗

PubMed1995

Aspergillus sphenoid sinusitis-induced orbital apex syndrome in HIV infection.

BACKGROUND: Orbital apex syndrome due to aspergillus sphenoid sinusitis is a rare condition. Human immunodeficiency virus (HIV) infection has recently been reported in aspergillus orbital abscess. To the authors' knowledge this is the first reported association of HIV with the orbital apex syndrome. METHODS: A 37-year-old HIV-infected man presented with headache, reduced vision and progressive ophthalmoplegia in the right eye. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed sphenoid sinusitis. Sphenoid sinus biopsy was performed. RESULTS: Light microscopy revealed infiltrative branching septate fungal hyphae. Fungal culture isolated Aspergillus fumigatus. CONCLUSION: Atypical fungal infection such as Aspergillus fumigatus sphenoid sinusitis should be suspected in HIV-infected patients with orbital apex syndrome.

Adult↗

PubMed1994

Thyroid hormone receptor-alpha inhibits retinoic acid-responsive gene expression and modulates retinoic acid-stimulated neural differentiation in mouse embryonic stem cells.

Thyroid hormone (T3) and retinoic acid (RA) are essential for normal vertebrate development and are known to coregulate several genes. Early development is predominantly retinoic acid sensitive, yet thyroid hormone receptor-alpha (T3R alpha) is expressed along with retinoic acid receptors (RAR)-alpha, -beta, and -gamma. To determine the role of unliganded T3R alpha in early development and on RA-stimulated neural development, we used homologous recombination techniques to inactivate both T3R alpha gene alleles in mouse embryonic stem (ES) cells. Loss of both T3R alpha alleles resulted in an increase in basal and RA-induced expression of the endogenous RA-responsive genes, RAR beta and alkaline phosphatase, which demonstrates that T3R alpha has an inhibitory effect on the RA response. A similar magnitude of T3R inhibition of the RA response was seen in transient transfection assays of RA response elements in both ES and assays of RA response elements in both ES and JEG cells. Cotransfection experiments were used to demonstrate that inhibition of the RA response could be mediated by T3R alpha 1. The addition of T3R alpha 1, but not the T3R alpha variant c-erbA alpha 2, to T3R alpha-null ES cells restored the inhibitory effect on RA-induced gene expression. RA-stimulated neural differentiation was seen in the wild-type, but not in T3R alpha-null ES, cells, consistent with reports of abnormal neural development as a consequence of premature RA stimulation. Our results demonstrate that the early expression of unliganded T3R alpha functions to modulate the RA response and RA-stimulated neural differentiation.

Alkaline Phosphatase↗

PubMed1989

The role of the suckling stimulus in regulating pituitary prolactin mRNA in the rat.

Prolactin (PRL) gene expression and the synthesis and secretion of PRL were examined in ovarian-intact lactating rats suckling eight pups on 10 days postpartum. Plasma samples were assayed for PRL concentrations, and pituitary glands were analyzed for total PRL content and PRL mRNA levels. We found that suckling-induced hyperprolactinemia was associated with very high levels of plasma PRL and a doubling in pituitary PRL mRNA levels, whereas pituitary PRL content was not changed. Removal of the suckling pups decreased plasma PRL concentrations 15-fold within 24 h. This decrease in PRL secretion was not accompanied by any significant change in pituitary PRL content. Evidently, both synthesis and secretion of PRL were decreased in the pituitary gland within 24 h following cessation of suckling, as pituitary PRL mRNA content had returned to diestrous levels at this time. To determine whether or not ovarian steroids might have contributed to the changes in PRL synthesis and secretion during lactation and after withdrawal of the suckling stimulus, the experiments were repeated in lactating rats ovariectomized (OVX) on day 2 postpartum. The results in these OVX rats were qualitatively similar to those described in ovarian-intact rats. We concluded from these findings that the stimulus of suckling induces increases in PRL mRNA levels in the pituitary which provides for the increased PRL synthesis accompanying increased PRL secretion. The cessation of suckling led to prompt decreases in PRL synthesis and secretion within 24 h.

Animals↗

PubMed1989

Dose response effects of pulsatile GnRH administration on restoration of pituitary GnRH receptors and pulsatile LH secretion during lactation.

Ovariectomized (OVX) rats suckling 8 pups have a complete suppression of pulsatile LH secretion and a decrease in pituitary GnRH receptor (GnRH-R) content. Removing the suckling stimulus for 24 h results in a sharp increase in GnRH-R and a restoration of pulsatile LH secretion. These findings suggest that the suckling stimulus induces a suppression of GnRH secretion, and removal of the suckling stimulus permits the restoration of GnRH secretion. Indeed, if GnRH antiserum is injected at the time of pup removal, the restoration of pituitary GnRH-R and LH secretion is prevented. The present studies were designed to test our hypothesis that the deficits in pituitary gonadotroph function observed during lactation are due to suckling-induced suppression of GnRH. Exogenous GnRH was administered in a pulsatile regimen to OVX lactating rats on days 10 and 11 postpartum, and the effects on pituitary GnRH-R levels, pituitary sensitivity to GnRH, and pulsatile LH secretion were assessed. GnRH doses of 0, 0.5, 2.0 or 5.0 ng/pulse were administered every 50 min for 24 h beginning on day 10. Administration of 0.5 ng GnRH/pulse for 24 h increased GnRH-R from 35 +/- 3 to 63 +/- 8 fmol/pituitary. There was a clear GnRH dose-related upregulation of GnRH-R to approach nonsuckling levels (140-160 fmol/pituitary) with the 5 ng GnRH dose. At the beginning of GnRH administration, the pituitary was very unresponsive to GnRH. Consistent LH pulses were only observed with 5 ng GnRH/pulse.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Expression of alpha-subunit and luteinizing hormone (LH) beta messenger ribonucleic acid in the rat during lactation and after pup removal: relationship to pituitary gonadotropin-releasing hormone receptors and pulsatile LH secretion.

Pituitary GnRH receptor (GnRH-R) levels and LH secretion are suppressed in the lactating rat. To determine if LH synthesis is also inhibited, we have measured LH subunit mRNA levels in the pituitary of lactating rats. We have also examined the temporal relationship among restoration of GnRH-R, LH secretion, and LH synthesis after withdrawing the sensory stimulus of suckling. Pituitary alpha-subunit and LH beta mRNA levels were sharply reduced on day 10 of lactation in both intact and ovariectomized (OVX) animals compared with those in cycling diestrous rats or OVX controls. Removal of the suckling stimulus from OVX animals led to significant increases in alpha-subunit and LH beta mRNA levels by 24 h. Upon removal of the suckling stimulus from intact rats, alpha-subunit mRNA levels were restored by 48 h, but LH beta mRNA levels did not return to diestrous levels until 72 h. Pituitary GnRH-R levels were clearly up-regulated within 1 day after pup removal. Some LH pulses were observed by 48 h, but consistent plasma LH pulses were not detected until 72 h. When pulsatile GnRH was administered during the 24 h after pup removal from intact rats, the regimen of pulsatile GnRH was successful in inducing LH secretion; however, the restoration of pulsatile LH was not accompanied by increases in alpha-subunit and LH beta mRNA levels. The present studies provide further evidence to support the hypothesis that during lactation, the suppression of pituitary gonadotroph function is mainly due to the loss of hypothalamic GnRH secretion. Our data also show that 1) the restoration of GnRH-R alone is not sufficient to activate LH subunit mRNA and LH secretion; 2) the normal restoration of pulsatile LH secretion and increases in LH subunit mRNA are temporally correlated, as increases in LH secretion appear to precede increases in LH subunit mRNA; and 3) the restoration of pituitary LH subunit mRNA levels and pulsatile LH secretion took longer in the intact rat than in the OVX rat, suggesting that ovarian steroids may play a role in the inhibitory effect of lactation.

Animals↗

PubMed1989

Modulation of pituitary gonadotropin-releasing hormone receptors during lactation in the rat.

Lactation is associated with a suppression of pituitary GnRH receptors (GnRH-R), and removal of the suckling stimulus for 24 h causes a 4- to 5-fold increase in GnRH-R. These studies were designed to examine the time course of recovery of GnRH-R after pup removal and to determine the roles that GnRH and PRL may play in modulating GnRH-R during lactation and after pup removal. All studies were performed on day 10 postpartum using ovariectomized rats suckling eight or zero pups. GnRH-R had more than doubled by 8 h after pup removal and had increased 4-5 times 16 h after pup removal to reach levels observed in nonsuckled controls. The increase in GnRH-R after pup removal resulted in a significant increase in pituitary responsiveness to GnRH. Maintenance of hyperprolactinemia after pup removal, by injecting ovine PRL, reduced the increase in GnRH-R by about 50%. Simultaneous administration of GnRH with ovine PRL restored GnRH-R to control levels. Administration of a potent antiserum to GnRH at the time of pup removal completely blocked the up-regulation of GnRH-R 24 h later. In the presence of the suckling stimulus and hyperprolactinemia, administration of pharmacological doses of GnRH caused a complete restoration of GnRH-R to levels observed in nonsuckled controls. Inhibition of suckling-induced PRL secretion with CB-154 caused a 2-fold increase in GnRH-R, and this effect could be completely reversed by simultaneous treatment with ovine PRL. These studies show that the suppression of pituitary GnRH-R during lactation appears to be due primarily to inhibition of GnRH secretion. After pup removal, recovery of GnRH-R occurs very rapidly, with recovery (4- to 5-fold increase) being completed by 16 h. Endogenous GnRH secretion is absolutely necessary for the up-regulation of GnRH-R to occur. The decrease in PRL levels after pup removal contributes to this process, most likely by causing an increase in GnRH secretion.

Animals↗

PubMed1989

Qualitative changes in luteinizing hormone and prolactin responses to N-methyl-aspartic acid during lactation in the rat.

The suppression during lactation of pulsatile LH release and pituitary GnRH receptors has been attributed to a primary deficit in hypothalamic GnRH release. In the present investigation we have attempted to characterize the responsiveness of the lactational hypothalamus using the excitatory amino acid receptor agonist N-methyl-aspartic acid (NMA) to stimulate LH and PRL secretion. Lactating rats were ovariectomized on day 2 postpartum, and their litters were adjusted to eight pups. Dual venous catheters were implanted 6-7 days later, and rats were fitted with protective tethers and jackets for chronic pulsatile infusions of GnRH and NMA. GnRH pulses (5 or 10 ng/pulse once every 50 min) were administered for 20 h to up-regulate GnRH receptors and restore pituitary responsiveness to GnRH. Rats were then infused with NMA (40 mg/kg BW.pulse) once every 50 min for four pulses or once every 2 h over a 24-h period. Blood samples were collected at 10-min intervals at times surrounding the final two GnRH pulses, the first several NMA pulses, and the final three NMA pulses 24 h later. Samples were analyzed for LH and PRL by RIA. Procedural control experiments were performed in normal adult rats with NMA administered at 20 mg/kg BW.pulse in males and at 20 and 40 mg/kg BW.pulse in females. Whereas normal rats responded to NMA pulses with unambiguous LH and PRL peaks, lactating rats failed to show LH responses either acutely or after 24 h of treatment. PRL responses to the drug depended upon the circulating levels of the hormone immediately preceding each NMA pulse. When levels were elevated (presumably due to intermittent suckling by the pups), NMA infusion resulted in an acute suppression of PRL. When PRL levels were low, NMA appeared to neither stimulate nor inhibit this hormone. These data suggest that GnRH release from the hypothalamus of the lactating rat is refractory to NMA stimulation, perhaps due to suckling-induced activation of endogenous opioid peptide or gamma-aminobutyric acid systems that could suppress GnRH neurons. Conversion of the PRL response from stimulation by NMA in normal animals to inhibition during lactation might be attributed to simultaneous activation of both dopamine neurons and the PRL-releasing factor system. According to this hypothesis, the response to NMA would be dominated by PRL-releasing factor in normal rats and by dopamine in lactating animals, which have a lower dopamine turnover rate and thus a greater potential for becoming activated by NMA.

Animals↗